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toshiba_acpi: Add extra check to backlight code

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Some Toshiba models (most notably Qosmios) come with an
incomplete backlight method where the AML code doesn't
check for write or read commands and always returns
HCI_SUCCESS and the actual brightness (and in some
cases the max brightness), thus allowing the backlight
interface to be registered without write support.

This patch changes the set_lcd_brightness function,
checking the returned values for values greater than
zero to avoid registering a broken backlight interface.

Signed-off-by: Azael Avalos <coproscefalo@gmail.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
This commit is contained in:
Azael Avalos 2014-08-04 09:21:01 -06:00 committed by Matthew Garrett
parent b58b9ffc95
commit f6aac65229
1 changed files with 17 additions and 4 deletions
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21
drivers/platform/x86/toshiba_acpi.c
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@ -872,7 +872,9 @@ static int lcd_proc_open(struct inode *inode, struct file *file)
static int set_lcd_brightness(struct toshiba_acpi_dev *dev, int value)
{
u32 hci_result;
u32 in[HCI_WORDS] = { HCI_SET, HCI_LCD_BRIGHTNESS, 0, 0, 0, 0 };
u32 out[HCI_WORDS];
acpi_status status;
if (dev->tr_backlight_supported) {
bool enable = !value;
@ -883,9 +885,20 @@ static int set_lcd_brightness(struct toshiba_acpi_dev *dev, int value)
value--;
}
value = value << HCI_LCD_BRIGHTNESS_SHIFT;
hci_write1(dev, HCI_LCD_BRIGHTNESS, value, &hci_result);
return hci_result == HCI_SUCCESS ? 0 : -EIO;
in[2] = value << HCI_LCD_BRIGHTNESS_SHIFT;
status = hci_raw(dev, in, out);
if (ACPI_FAILURE(status) || out[0] == HCI_FAILURE) {
pr_err("ACPI call to set brightness failed");
return -EIO;
}
/* Extra check for "incomplete" backlight method, where the AML code
* doesn't check for HCI_SET or HCI_GET and returns HCI_SUCCESS,
* the actual brightness, and in some cases the max brightness.
*/
if (out[2] > 0 || out[3] == 0xE000)
return -ENODEV;
return out[0] == HCI_SUCCESS ? 0 : -EIO;
}
static int set_lcd_status(struct backlight_device *bd)